Wiper and method for manufacturing the same

ABSTRACT

Disclosed is a wiper which is which is highly retentive of water, soft to the touch, and improved in sheet strength and a method for manufacturing the same. An interlining layer contains pulp fibers, first and second surfacing layers contain non-fusible fibers, and a reinforcing layer contains fusible fibers and rayon fibers. The fusible fibers are fusion-bonded but the non-fusible fibers remain unfused. Sheet surfaces are free from the fusible fibers.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a wiper intended to be used for wipingthe human body, furniture, home fixtures and so on in a pre-moistened ordry state and a method for manufacturing the same.

2. Description of the Related Art

Nonwoven wipers have been widely used to wipe the human body, furniture,home fixtures and so on. Such wipers may be used in a dry ,state toabsorb water during use or in a pre-moistened state. In either case,nonwoven wipers are formed of hydrophilic fibers such as rayon andsynthetic resin fibers.

Japanese Patent No. 3183818 discloses a wet tissue in which aninterlining layer is disposed between upper and lower layers. The upperand lower layers contain hydrophobic fibers at a higher proportion thanhydrophilic fibers whereas the interlining layer contains hydrophilicfibers at a higher proportion than hydrophobic fibers. Fibersconstituting these layers are entangled, fusion-bonded or entangled andfusion-bonded to impart a sufficient strength to a nonwoven fabric. Inthis wet tissue, the hydrophilic fibers function to retain water. Withthe hydrophobic fibers appearing on the tissue surfaces, moreover, thewet tissue is allowed to easily separate from another wet tissue.

Japanese Patent No. 3333718 discloses a wiper stack in which each wipercomprises two fibrous web layers of hydrophilic fibers, polyester fibersand heat-fusible fibers (or thermally bondable fibers) and a pulp fiberlayer interposed therebetween. These layers are entangled and integratedtogether by high-pressure water streams, and the heat-fusible fibers arefusion-bonded to each other. Because the pulp fiber layer is provided asan interlining layer, this wiper is capable of retain much water anddoesn't feel sticky to the touch.

In these wipers disclosed in Japanese Patent Nos. 3183818 & 3333718, theheat-fusible fibers are fusion-bonded to each other in the upper andlower surfacing layers between which the interlining layer is interposedto retain water. Thus, the fusion-bonded fibers appear on the sheetsurface and make the sheet surface hard due to immovability.Accordingly, the wipers tend to irritate the skin when used for wipingthe human body.

Unlike the Japanese Patent Nos. 3183818 & 3333718, there may bedeveloped a wet tissue not containing heat-fusible fibers. However, justentangling hydrophilic fibers and synthetic resin fibers will result indecreased sheet strength, particularly decreased wet strength, so thatwhen the wet tissue is used for wiping, it is likely that fibers fallout of the sheet surface or the sheet itself is broken.

SUMMARY OF THE INVENTION

The present invention has been developed in view of the shortcomings inthe prior art set forth above. It is therefore an object of the presentinvention to provide a wiper which is highly retentive of water, soft tothe touch, and improved in sheet strength.

Another object of the present invention is to provide a method formanufacturing the same.

According to a first aspect of the invention, there is provided a wiperin the form of a sheet comprising:

-   -   a first surfacing layer appearing on one sheet surface;    -   a second surfacing layer appearing on the other sheet surface;    -   a reinforcing layer comprising fusible fibers; and    -   an interlining layer comprising hydrophilic fibers, the        reinforcing layer and the interlining layer being located        between the first and second surfacing layers, the first and        second surfacing layers comprising non-fusible fibers whose        surface has a higher melting point than that of the fusible        fibers or is not allowed to melt,    -   wherein the fusible fibers are fusion-bonded while the        non-fusible fibers remain unfused.

The wiper of the invention is highly retentive of water due to thepresence of the interlining layer comprised of hydrophilic fibers. Sincethe surfacing layers are comprised of non-fusible fibers, fibers locatedon the sheet surfaces are kept in a relatively freely movable state toprovide a soft feeling. Thus, the sheet surfaces hardly irritate theskin when used for wiping the human body, and the coefficient offriction between the sheet surfaces and an object to be cleaned islowered to facilitate sliding. On the other hand, the wiper has anincreased sheet strength because the reinforcing layer comprised offusible fibers is disposed inside the sheet and the fusible fibers arefusion-bonded.

Preferably, the hydrophilic fibers contained in the interlining layerare cellulosic fibers having a fiber length equal to or less than 10 nunand the interlining layer has a higher density than the first and secondsurfacing layers. This leads to higher water retentivity of the sheetand enables water contained in the interlining layer to gradually comeout of the sheet surfaces when a pressure is exerted thereon duringwiping.

Also preferably, the non-fusible fibers constituting the first surfacinglayer and/or the second surfacing layer are at least either of syntheticresin fibers or cellulosic fibers having a fiber length in the range of20 to 70 mm. If the surfacing layer is comprised only or mainly ofsynthetic resin fibers, the sheet surface can be prevented from beingexcessively moistened to provide a sticky feeling to the skin. If thesurfacing layer is comprised only or mainly of cellulosic fibers, on theother hand, water adhered to an object to be cleaned can be readilyabsorbed when the wiper is used in a dry state.

Here, the reinforcing layer may contain non-fusible fibers in additionto the fusible fibers. In this case, the non-fusible fibers arepreferably hydrophilic fibers, more preferably cellulosic fibers havinga fiber length in the range of 20 to 70 mm.

According to a second aspect of the present invention, there is provideda method for manufacturing a wiper comprising:

-   -   forming a multilayered fibrous web with a reinforcing        layer-forming fibrous web and an interlining layer-forming        fibrous web located between a first surfacing layer-forming        fibrous web and a second surfacing layer-forming fibrous web,        the reinforcing layer-forming fibrous web comprising fusible        fibers, the interlining layer-forming fibrous web comprising        hydrophilic fibers, the first surfacing layer-forming fibrous        web and the second surfacing layer-forming fibrous web        comprising non-fusible fibers whose surface has a higher melting        point than that of the fusible fibers or is not allowed to melt,    -   integrating the multilayered fibrous web through a water-jet        treatment; and    -   heat-treating the integrated multilayered fibrous web at such a        temperature as to melt the surface of the fusible fibers but not        melt the surface of the non-fusible fibers.

According to this method, a wiper which is highly retentive of water,soft to the touch, and improved in sheet strength can be relativelyeasily manufactured.

In the above method, preferably, cellulosic fibers having a fiber lengthequal to or less than 10 mm are deposited to form the interlininglayer-forming fibrous web. Also preferably, at least either of syntheticresin fibers or cellulosic fibers having a fiber length in the range of20 to 70 mm are deposited to form the first surfacing layer-formingfibrous web and/or the second surfacing layer-forming fibrous web. Here,the reinforcing layer-forming fibrous web may contain non-fusible fibersin addition to the fusible fibers.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be understood more fully from the detaileddescription given hereinafter and from the accompanying drawings of thepreferred embodiments of the present invention, which, however, shouldnot be taken to be limitative to the invention, but are for explanationand understanding only.

In the drawings:

FIG. 1 is an enlarged sectional view of a wiper according to a firstembodiment of the present invention;

FIG. 2 is an enlarged sectional view of a multilayered fibrous webprepared in a process for manufacturing the wiper of the firstembodiment;

FIG. 3 is an enlarged sectional view schematically showing the internalstructure of the wiper of the first embodiment;

FIG. 4 is an enlarged sectional view of a wiper according to a secondembodiment of the present invention; and

FIG. 5 is an enlarged sectional view of a multilayered fibrous webprepared in a process for manufacturing the wiper of the second.embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention will be discussed. hereinafter in detail in termsof the preferred embodiments according to the present invention withreference to the accompanying drawings. In the following description,numerous specific details are set forth in order to provide a thoroughunderstanding of the present invention. It will be obvious, however, tothose skilled in the art that the present invention may be practicedwithout these specific details. In other instance, well-known structuresare not shown in detail in order to avoid unnecessary obscurity of thepresent invention.

FIG. 1 is an enlarged. sectional view of a wiper 1 according to a firstembodiment of the present invention; FIG. 2 is an enlarged sectionalview of a multilayered fibrous web 1 a prepared in the process formanufacturing the wiper 1; and FIG. 3 is an enlarged sectional viewschematically showing the internal structure of the wiper 1.

First of all, fibers constituting layers of the wiper 1 will bedescribed. Fibers as used herein are broadly divided into “fusiblefiber” and “non-fusible fiber”. The term “non-fusible fiber” includes“hydrophilic fiber” and “hydrophobic fiber”. The term “hydrophilicfiber” includes “cellulosic fiber” and “synthetic resin fiber treated tobe hydropllilic”. That is, the term “non-fusible fiber” refers to fiberwhose surface has a higher melting point than that of the “fusiblefiber” or is not allowed to melt. Meanwhile, the term “fusible fiber”includes synthetic resin fiber treated to be hydrophilic and hydrophobicfibers (hydrophobic synthetic resin fibers).

Referring to FIG. 1, the wiper 1, being a single nonwoven fabric, has afirst sheet surface 2 and a second. sheet surface 3. The wiper 1 isintended to be supplied as a wet tissue pre-moistened with water orchemicals or a dry tissue capable of absorbing water during use. It mayalso be used for wiping a toilet, kitchen fixtures, furniture and so onin a dry or pre-moistened state. The wiper 1 may be used for wiping inany suitable manner. For example, two or more sheets of wiper 1 may bestacked and folded.

As shown in FIGS. 1 and 3, the wiper 1 can be divided into four layers:an interlining layer 11; a first surfacing layer 12 appearing on thefirst surface 2; a second surfacing layer 13 appearing on the secondsurface 3; and a reinforcing layer 14 located between the firstsurfacing layer 12 and the interlining layer 11.

As will be described later with reference to FIG. 2, the wiper 1 ismanufactured by subjecting a multilayered fibrous web to a water-jettreatment and heat-treating the hydroentangled fibrous web. Where waterjets are applied, fibers tend to be entangled not only within theindividual layers but also across the layers. Where water jets areapplied, furthermore, hydrophilic fibers such as pulp having a fiberlength equal to or less than 10 mm, e.g., in the range of 0.3-10 mm or1-10 mm, tend to migrate to another layer (or mix with other fibers) dueto high pressure of water streams.

Accordingly, it is likely that the interlining layer 11, the firstsurfacing layer 12, the second surfacing layer 13 and the reinforcinglayer 14 cannot be dearly divided, and therefore in FIG. 1, boundariesbetween the layers are indicated by dashed lines. Thus, the firstsurfacing layer, the second surfacing layer, the interlining layer andthe reinforcing layer according to the invention may have ill-definedboundaries.

The interlining layer 11 is mainly constituted of hydrophilic fibers.For. the hydrophilic fibers, there may be used natural fibers such aspulp and cotton (cellulosic fibers) having a fiber length equal to orless than 10 mm, for example in the range of 1-10 mm, and regeneratedfibers such as rayon (cellulosic fibers) having a fiber length in therange of 20-70 mm It is also possible to use synthetic resin fibers thatare treated to be hydrophilic such as by applying a hydropbilizingagent, e.g., surfactant to the fiber surface or kneading the materialresin with such a hydrophilizing agent. Among them, preferably used arethe natural fibers. It should be noted that the interlining layer 11 maycontain hydrophobic synthetic resin fibers to such a degree as not toimpair water retentivity.

The reinforcing layer 14 is mainly constituted of fusible fibers aloneor in combination with the hydrophilic fibers. The fusible fibers have alow-melting resin such as polyethylene or low-melting polypropyleneappearing on their surface. Examples of the fusible fibers includemonocomponent fibers of polyethylene, monocomponent fibers ofpolypropylene, sheath/core bicomponent fibers of which the core ispolyethylene terephthalate and the sheath is polyethylene, sheath/corebicomponent fibers of which the core is polypropylene and the sheath ispolyethylene, sheath/core bicomponent fibers of which the core ishigh-melting polypropylene and the sheath is low-melting polypropylene,side-by-side bicomponent fibers composed of polyethylene terephthalateand polyethylene, and side-by-side bicomponent fibers composed ofpolypropylene and polyethylene.

The first surfacing layer 12 and the second surfacing layer 13 aremainly constituted of non-fusible fibers. The non-fusible fibers may besynthetic resin fibers whose surface has a higher melting point thanthat of the above-mentioned fusible fiber, preferably by 20 degreescentigrade. Examples of the non-fusible synthetic resin fibers includepolypropylene fibers, polyethylene terephthalate fibers and nylonfibers. Preferably, these fibers are hydrophobic. In addition, oralternatively, cellulosic fibers, preferably regenerate fibers such asrayon having a fiber length in the range of 20-70 mm, may be used as thenon-fusible fibers. If desired, the first surfacing layer 12 and thesecond surfacing layer 13 may be of different kinds of fibers ordifferent blending ratios.

If the non-fusible fibers constituting the first and second surfacinglayers 12 and 13 are only the hydrophobic synthetic resin fibers or theblending ratio of the hydrophobic synthetic resin fibers to total weightof the non-fusible fibers constituting the first and second surfacinglayers 12 and 13 is equal to or greater than 60%, the sheet surface canbe prevented from being excessively moistened (or soaked) with water orchemicals oozing out of the interlining layer 11 when the wiper is usedin a pre-moistened state. This also results in preventing a stickyfeeling to the skin, as well as undesirable adhesion of the wiper to anobject to be cleaned or another wiper.

If the non-fusible fibers constituting the first and second surfacinglayers 12 and 13 are only the hydrophilic cellulosic fibers or theblending ratio of the hydrophilic cellulosic fibers to total weight ofthe non-fusible fibers constituting the first and second surfacinglayers 12 and 13 is equal to or greater than 60%, on the other hand,water adhered to the skin or another object to be cleaned can be readilyabsorbed and introduced into the interlining layer 11 when the wiper isused in a dry state.

Through a water-jet treatment, these layers 11-14 are integrated into asingle nonwoven fabric. If the interlining layer 11 is mainlyconstituted of cellulosic fibers such as pulp, the cellulosic fibers canalso be bound to each other through hydrogen bonding due to the presenceof hydroxyl group on fiber surface.

The fusible fibers are fusion-bonded to each other or to the otherfibers. Fusion bonds due to the fusible fibers can be found mainly inthe reinforcing layer 14. On the other hand, the non-fusible fibers arekept in a relatively freely movable state.

FIG. 3 schematically shows an exemplary structure of the wiper 1.

In this embodiment, the interlining layer 11 is constituted of pulpfibers 21, the reinforcing layer 14 is constituted of fusible fibers 22and rayon fibers (cellulosic fibers) 23 having a fiber length in therange of 20-70 mm. The fusible fibers 22 are fusion-bonded to each otheror to the rayon fibers 23. The first surfacing layer 12 and the secondsurfacing layer 13 are constituted of non-fusible hydrophobic syntheticresin fibers 24 and rayon fibers (cellulosic fibers) 25 having a fiberlength in the range of 20-70 mm. Thus, the first and second surfaces 2and 3 of the wiper 1 are mainly formed of the synthetic resin fibers 24and the rayon fibers 25, which are both non-fusible fibers, and arecompletely or substantially free from the fusible fibers 22. That is,even if the fusible fibers 22 appear on the first and second surfaces 2and 3, the ratio of the fusible fibers 22 to the non-fusible fibers istoo small to have any effect on the first and second surfaces 2 and 3.

Here, the density of the pulp fibers 21 in the interlining layer 11 ishigher than the fiber densities of the first surfacing layer 12, thesecond surfacing layer 13 and the reinforcing layer 14.

Next, a method for manufacturing the wiper 1 will be described.

The multilayered fibrous web 1 a shown in FIG. 2 is formed on a conveyorbelt of a net, which is generally called “wire”, or a conveyor belt of aperforated plate (not shown). The multilayered fibrous web 1 a is formedby stacking a second surfacing layer-forming fibrous web 13 a, aninterlining layer-forming fibrous web 11 a, a reinforcing layer-formingfibrous web 14 a and a first surfacing layer-forming fibrous web 12 a inthe order named above upwardly from the conveyor belt.

The second surfacing layer-forming fibrous web 13 a, the first surfacinglayer-forming fibrous web 12 a and the reinforcing layer-forming fibrousweb 14 a are all formed by depositing fibers by a carded process. Boththe second surfacing layer-forming fibrous web 13 a and the firstsurfacing layer-forming fibrous web 12 a are only of non-fusible fibers.More specifically, the fibrous webs 12 a, 13 a are formed of a blend of50-100 wt. % of hydrophobic synthetic resin fibers and 0-50 wt. % ofrayon fibers (hydrophilic fibers) having a fiber length in the range of20-10 mm. On the other hand, the fibrous web 14 a is formed of a blendof 50-100 wt. % of fusible fibers and 0-50 wt. % of rayon fibers(hydrophilic fibers) having a fiber length in the range of 20-70 mm.

The interlining layer-forming fibrous web 11 a is formed only ofhydrophilic fibers having a fiber length equal to or less than 10 mm,e.g., in the range of 0.3-10 mm or 1-10 mm. For example, at least eitherof pulp or cotton may be deposited by air-forming.

The multilayered fibrous web 1 a thus formed on the conveyor belt isthen subjected to water jets which are applied from above the firstsurfacing layer-forming fibrous web 12 a and optionally from below thesecond surfacing layer-forming fibrous web 13 a, thereby integrating thefibrous webs into a single nonwoven fabric.

Thereafter, the obtained nonwoven fabric is heat-treated, wherein theheating temperature is set to melt the surface of the fusible fibers butnot melt the surface of the non-fusible fibers. Through the heattreatment, the fusible-fibers are fusion-bonded to each other or to theother fibers. Since the fusible fibers are initially contained only inthe reinforcing layer-forming fibrous web 14 a, the fusion-bonded fibersare present mainly in the reinforcing layer 14 of the completed wiper 1.Moreover, since the reinforcing layer 14 is adjacent to the interlininglayer 11, the pulp fibers etc. in the interlining layer 11 can also beheld by fusion-bonding power of the fusible fibers in the reinforcinglayer 14, which contributes to increased sheet strength, particularlyincreased wet strength.

The wiper 1 of FIGS. 1 and 3 is highly retentive of water due to thepresence of hydrophilic fibers such as pulp in the interlining layer 11.In addition, since the interlining layer 11 has a higher fiber densitythan not only the first and second surfacing layers 12, 13 but also thereinforcing layer 14, the wiper 1 is allowed to retain much water in theinterlining layer 11. Furthermore, hydrophilic fibers such as rayoncontained in the first and second surfacing layers 12, 13 and thereinforcing layer 14 also contribute to high water retentivity of thewiper 1 and facilitate migration of water between the sheet center andthe sheet surfaces 2, 3. Since the fusible fibers hardly appear on thefirst and second surfaces 2, 3, as set forth above, the first and secondsurfaces 2, 3 can be made soft, for example, so as not to irritate theskin when used for wiping the human body. In addition, the coefficientof friction between the first and second surfaces 2, 3 and an object tobe cleaned is lowered to facilitate sliding.

In the wiper 1, the fusible fibers, which are fusion-bonded to eachother or to the other fibers in the reinforcing layer 14 as well as tothe fibers constituting the first surfacing layer 12 and the interlininglayer 11, contribute to the increased sheet strength, particularly theincreased wet strength.

The wiper 1 has a basis weight in, but not limited to, the range of 30to 100 g/m², wherein the interlining layer 11 may have a basis weight inthe range of 10 to 60 g/m² and the reinforcing layer 14 have a basisweight in the range of 5 to 50 g/m².

FIG. 4 is an enlarged sectional view of a wiper 101 according to asecond embodiment of the present invention, and FIG. 5 is an enlargedsectional view of a multilayered fibrous web 101 a prepared in theprocess for manufacturing the wiper 101.

The wiper 101 of FIG. 4 includes two reinforcing layers 14, 14 on bothsides of the interlining layer 11, wherein one reinforcing layer 14 iscovered with the first surfacing layer 12 and the other reinforcinglayer 14 is covered with the second surfacing layer 13.

As shown in FIG. 5, the multilayered fibrous web 101 a is formed bystacking a second surfacing layer-forming fibrous web 13 a, areinforcing layer-forming fibrous web 14 a, an interlining layer-formingfibrous web 11 a, a reinforcing layer-forming fibrous web 14 a and afirst surfacing layer-forming fibrous web 12 a one on top of the other.

The individual fibrous webs are constituted in the same manner as in thefirst embodiment and the wiper 1 is manufactured also in the same manneras in the first embodiment.

Since the reinforcing layers 14, 14, in which the fusible fibers arefusion-bonded as set forth above, are provided on both sides of theinterlining layer 11, the sheet strength of the wiper 101 according tothe second embodiment can be further enhanced. When the interlininglayer 11 containing pulp fibers or the like is moistened with water,hydrogen bonding between the pulp fibers or the like tends to beweakened. In the wiper 101, however, the sheet strength can bemaintained more reliably even in a moistened state because thefusion-bonded reinforcing layers 14, 14 are disposed on both side of theinterlining layer 11.

Although the present invention has been illustrated and described withrespect to exemplary embodiments thereof, it should be understood bythose skilled in the art that the foregoing and various other changes,omission and additions may be made therein and thereto, withoutdeparting from the spirit and scope of the present invention. Forexample, two or more interlining layers 11 may be provided in the wipersuch that the second surfacing layer 13, the interlining layer 11, thereinforcing layer 14, the interlining layer 11 and the first surfacinglayer 12 are stacked one on top of the other or such that the secondsurfacing layer 13, the interlining layer 11, the reinforcing layer 14,the interlining layer 11, the reinforcing layer 14 and the firstsurfacing layer 12 are stacked one on top of the other. It is alsopossible to stack the second surfacing layer 13, the reinforcing layer14, the interlining layer 11, the reinforcing layer 14, the interlininglayer 11, the reinforcing layer 14 and the first surfacing layer 12 oneon top of the other.

The present invention should not be understood as limited to thespecific embodiments set out above but to include all possibleembodiments which can be embodied within a scope encompassed andequivalent thereof with respect to the feature set out in the appendedclaims.

1-5. (canceled)
 6. A method for manufacturing a wiper comprising:forming a multilayered fibrous web with a reinforcing layer-formingfibrous web and an interlining layer-forming fibrous web located betweena first surfacing layer-forming fibrous web and a second surfacinglayer-forming fibrous web, the reinforcing layer-forming fibrous webcomprising fusible fibers, the interlining layer-forming fibrous webcomprising hydrophilic fibers, the first surfacing layer-forming fibrousweb and the second surfacing layer-forming fibrous web comprisingnon-fusible fibers whose surface has a higher melting point than that ofthe fusible fibers or is not allowed to melt, integrating themultilayered fibrous web through a water-jet treatment; andheat-treating the integrated multilayered fibrous web at such atemperature as to melt the surface of the fusible fibers but not meltthe surface of the non-fusible fibers.
 7. A method according to claim 6,wherein cellulosic fibers having a fiber length equal to or less than 10mm are deposited to form the interlining layer-forming fibrous web.
 8. Amethod according to claim 6, wherein at least either of synthetic resinfibers or cellulosic fibers having a fiber length in the range of 20 to70 mm are deposited to form the first surfacing layer-forming fibrousweb.
 9. A method according to claim 6, wherein at least either ofsynthetic resin fibers or cellulosic fibers having a fiber length in therange of 20 to 70 mm are deposited to form the second surfacinglayer-forming fibrous web.
 10. A method according to claim 6, whereinthe reinforcing layer-forming fibrous web contains non-fusible fibers inaddition to the fusible fibers.